1. Field of the Invention
This invention relates to nestable article shipping racks and end restraints for limiting longitudinal motion of the articles.
2. Discussion of the Technical Problems
Articles, e.g., glass sheets, automotive sidelites or automotive windshields are transported in racks. In general, the racks include a backwall having back supports secured to a base having edge supports to support the articles on an edge tilted toward the backwall. This arrangement provides stacking stability and counteracts transportation oscillating forces that oscillate the articles about their bottom edge toward and away from the backwall.
Transportation longitudinal forces which move the articles toward and away from the sides of the rack are dampened by end restraints mounted on the base.
After the racks are unloaded, they are stored for return shipment. Because the end restraints extend beyond the base and the back supports extend out from the backwall the racks are not nestable. In other words, individual racks cannot be stacked within other racks. As can be appreciated, cost of shipping empty racks by rail or truck and the storage of empty racks is reduced when racks are nestable. This is because more empty racks can be shipped in a railcar, truck and/or stored.
Another limitation of the prior art racks is the force absorbing facilities of the end restraints. Typical prior art end restraints are taught in U.S. Pat. Nos. 3,147,860 and 3,809,234. In general the end restraint of U.S. Pat. No. 3,809,234 includes a saddle that is mounted on a pair of stationary inclined mounting fixtures. One drawback is that the end restraints are not economically adaptable for different article edge contours. The matching of the contour of the engaging surface of the edge restraint to the article edge contour is critical because a mismatch can set up areas of point stress that can fracture the article edge during transit. In the prior art, the mismatch problem can be eliminated by providing various end restraints for the various article edge contour of the articles to be shipped. This is expensive from an inventory standpoint.
Another drawback of the prior art end restraints is that the force of the articles is absorbed by direct contact with the rubber pad of the saddle. Directly absorbing the force by the rubber pad requires that the saddle and mounting fixture be structurally strong. Increasing the structural strength of the end restraints increases the weight of the rack and the cost to fabricate the rack.
Therefore, it would be advantageous if nestable racks were available to reduce the cost of returning empty racks to the supplier and storing empty racks. Further it would be advantageous if an end restraint was available that does not have the limitations of the prior art end restraints.